3D Seismic Refraction Travel-Time Tomography beneath the Middle-Lower Yangtze River Region
3D Seismic Refraction Travel-Time Tomography beneath the Middle-Lower Yangtze River Region
复制标题
长江中下游地区3D地震折射走时层析成像
DOI：
10.1785/0220170245
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发表时间：
2018
影响因子：
3.3
通讯作者：
王夫运
中科院分区：
文献类型：
--
作者：
田晓峰;杨卓欣;王宝善;姚华建;王夫运
应用初至地震层析成像技术，对中国东部、安徽长江中下游地区(∼)200x150 km的三维地震折射实验数据进行了处理。本实验利用大体积气枪发射的地震能量对地壳速度结构进行成像。在几乎固定的地点叠加300多次重复发射的波形后，气枪发射产生的初至相位可以清楚地追溯到160公里以上的距离。采用正则化的非线性走时反演算法，建立了具有光滑最小结构的三维压缩速度模型。对选取的2549个具有自动确定不确定性的首发出行时间进行了反演。我们最终的优选速度模型与区域地质单位有很好的对应关系。该模型还包含区域矿田下的高速异常。棋盘分辨率测试表明，10公里的横向速度异常可以在模式的大部分地区恢复。我们的研究成功地展示了在陆地水体中使用环境友好型气枪震源进行高分辨率地壳结构成像的经典地震勘探。
We applied first-arrival seismic tomography to 3D seismic refraction experimental data observed in the middle-lower Yangtze River region, Anhui Province, eastern China, in an area ∼200 km by 150 km. This experiment used the seismic energy released by large-volume airgun shots to image crustal velocity structure. The first-arrival phases generated by airgun shots can be clearly traced to a distance larger than 160 km after stacking waveforms over 300 repetitive shots at nearly fixed sites. A regularized nonlinear travel-time inversion algorithm was used to develop a 3D compressional velocity model with smooth minimum structure. A total of 2549 picked first-arrival travel times with automatically determined uncertainty were inverted. Our final preferred velocity model shows a good correspondence with regional geological units. The model also contains high-velocity anomalies beneath regional ore deposit fields. Checkerboard resolution tests show that 10 km lateral velocity anomalies can be recovered throughout most of the model. Our study has successfully demonstrated a classic seismic survey using environmentally friendly airgun sources in a land-based water body for high-resolution imaging of crustal structures.